Martin Sprocket 1030687M MTO SPROCKET ROLLER B 120B9 1 1/4" BORE (1.250/1.251) 5/16" X 5/32" NON-STD KEYWAY 1.391/1.401 L.A.B. (2) 5/16-18 UNC SET SCREWS SPROCKET FOR ANSI 120-1 CHAIN 9 TEETH5.020" O.D., 4.386" P.D."B" STYLE2 1/4" O.A.L.3 3/8" HUB O.D. X 1.334" LENGTHSOLID CONSTRUCTIONCARBON STEEL